Indications
1. Functional Impairment
Forearm rotation deficit >50% compared to the contralateral side.
Angular deformity >10° (significantly affects rotation).
Rotational deformity >10° (measurably affects pronation/supination).
2. Joint & Biomechanical Issues
DRUJ instability or incongruity secondary to the malunion.
Symptomatic ulnocarpal impaction due to positive ulnar variance.
Pain from altered mechanics in the wrist, DRUJ, or interosseous membrane.
Timing: The optimal surgical window is between 6 weeks and 12 months post-fracture.
Biomechanics (High-Yield)
The radius and ulna function as a mechanically coupled unit; any deformity disrupts forearm rotation.
The central band of the interosseous membrane (IOM) is the primary stabilizer; altered tension from malunion leads to rotation loss independent of angular deformity. Critical thresholds: Angular deformity >10° or rotational deformity >10° leads to significant functional impairment.
Surgical Options
1. Opening Wedge Osteotomy
Indications: Angular deformities requiring length restoration.
Technique: Opens the concave side; requires a structural bone graft (iliac crest or allograft).
Advantage: Preserves bone length.
2. Closing Wedge Osteotomy
Indications: Angular deformities where modest shortening is acceptable.
Technique: Removes a wedge from the convex side.
Advantage: Reliable union with bone-to-bone contact; no graft needed.
3. Derotational Osteotomy
Indications: Pure rotational deformities.
Technique: Transverse cut with controlled rotation to neutral.
4. Dome Osteotomy
Indications: Multiplanar deformities.
Technique: Curved cut allowing simultaneous angular and rotational correction without changing length.
Limitations: Technically demanding.
5. Step-Cut Osteotomy
Indications: Complex multiplanar malunions with length discrepancy.
Technique: Z-shaped cut that increases contact area and provides inherent rotational stability.
Preoperative Planning
Identify CORA (Center of Rotation of Angulation): Placing the osteotomy at the CORA provides pure angular correction without translation.
Measure Rotation: Plain X-rays underdiagnose rotation; use CT to measure the bicipital tuberosity angle relative to the radial styloid.
Assess Length: Always compare to the contralateral X-ray. 👉 Virtual Surgical Planning (VSP): 3D CT reconstruction and patient-specific cutting guides are standard for complex deformities, reducing mean residual angular error from 8.1° to 3.2°.
Postoperative Management
Stable fixation allows for early active-assisted ROM from day 1–3.
Use a posterior splint for comfort only; do not unnecessarily immobilize.
Begin resistive exercises at week 6 when callus is visible.
Complications
Stiffness: The most common functional complication (prevented by early ROM).
Non-union (2–10%): Due to inadequate fixation, infection, or graft failure.
Hardware prominence: Very common with ulnar plates.
Radioulnar synostosis (~1–3%): Risk increases if a single longitudinal incision is used for both bones.
Nerve injury: AIN (volar approach), PIN (dorsal approach).
Prognosis
Good outcomes in 75–90% of cases with proper indications and technique.
Expect a 40–60° improvement in forearm rotation.
Early malunion (<12 months) yields better outcomes than late interventions with secondary joint changes.
Pits & Pearls
Angular malunion >10° requires correction even in the absence of other symptoms.
Rotational deformities are highly underdiagnosed; always use CT for bicipital tuberosity positioning.
Dual plating is mandatory for both-bone forearm malunions (one plate per bone).
For both-bone corrections, completely fix the radius before starting the ulna to prevent intraoperative positioning difficulties.
Cutting at the CORA = pure angular correction without translation.
Stable fixation means early motion; stiffness is a preventable complication.
Pitfalls
Using a single incision for both bones significantly increases the risk of radioulnar synostosis; separate incisions are mandatory.
Prolonged immobilization after stable fixation leads to stiffness.
Failing to assess and correct the rotational component, which doesn't remodel even in children.
Inadequate preoperative planning leading to residual deformity or overcorrection.
Mini Decision Algorithm
Condition | Decision | Action |
|---|---|---|
Forearm malunion detected | Assess | Quantify rotation loss — measure pro/supination vs contralateral AP + lateral forearm X-ray; CT if rotational component suspected |
Mild deformity + minimal symptoms | Observe | Annual follow-up — reassess if functional deficit progresses Angular <10°, rotation loss <20% — observation acceptable |
Functional limitation present | Plan osteotomy | Corrective osteotomy — type based on deformity pattern Contralateral X-ray as planning reference; CORA analysis |
Rotational deformity | CT-based correction | Derotational osteotomy — bicipital tuberosity reference Rotational malunion does NOT remodel — always requires correction |
Multiplanar deformity | Advanced osteotomy | Dome osteotomy or double-level osteotomy ± 3D VSP Patient-specific guides improve angular accuracy (3.2° vs 8.1° conventional) |
References:
Schemitsch EH, Richards RR. The effect of malunion on functional outcome after plate fixation of fractures of both bones of the forearm. J Bone Joint Surg Am. 1992.
Tarr RR, Garfinkel AI, Sarmiento A. The effects of angular and rotational deformities of both bones of the forearm. J Bone Joint Surg Am. 1984.
Matthews LS, Kaufer H, Garver DF. The effect on supination-pronation of angular malalignment of fractures of both bones of the forearm. J Bone Joint Surg Am. 1982.
Prommersberger KJ, van Schoonhoven J. Corrective osteotomy for malunited fractures of the forearm. J Hand Surg. 2006.
Roth KC, Denk K, Colaris JW. Computer-assisted corrective osteotomy of forearm malunions. J Hand Surg Eur. 2017.